In vitro and in vivo leishmanicidal activity of a ruthenium nitrosyl complex against Leishmania (Viannia) braziliensis

First-Row Transition 7-Oxo-5-phenyl-1,2,4-triazolo[1,5-a]pyrimidine Metal Complexes: Antiparasitic Activity and Release Studies

Leishmaniasis and Chagas disease are still considered neglected illnesses due to the lack of investment in research, despite the fact that almost one million new cases are reported every year. Four 7-oxo-5-phenyl-1,2,4-triazolo[1,5-a]pyrimidine (HftpO) first-row transition complexes (Cu, Co, Ni, Zn) have been studied for the first time in vitro against five different species of Leishmania spp. (L. infantum, L. braziliensis, L. donovani, L. peruviana and L. mexicana) as well as Trypanosoma cruzi, showing higher efficacy than the reference commercial drugs. UV and luminescence properties were also evaluated. As a proof of concept, anchoring of a model high-effective-metal complex as an antiparasitic agent on silica nanoparticles was carried out for the first time, and drug-release behaviour was evaluated, assessing this new approach for drug vehiculation.

Nitroprusside─Expanding the Potential Use of an Old Drug Using Nanoparticles

For more than 70 years, sodium nitroprusside (SNP) has been used to treat severe hypertension in hospital emergency settings. During this time, a few other clinical uses have also emerged such as in the treatment of acute heart failure as well as improving mitral incompetence and in the intra- and perioperative management during heart surgery. This drug functions by releasing nitric oxide (NO), which modulates several biological processes with many potential therapeutic applications. However, this small molecule has a short lifetime, and it has been administered through the use of NO donor molecules such as SNP. On the other hand, SNP also has some setbacks such as the release of cyanide ions, high water solubility, and very fast NO release kinetics. Currently, there are many drug delivery strategies that can be applied to overcome many of these limitations, providing novel opportunities for the use of old drugs, including SNP. This Perspective describes some nitroprusside properties and highlights new potential therapeutic uses arising from the use of drug delivery systems, mainly silica-based nanoparticles. There is a series of great opportunities to further explore SNP in many medical issues as reviewed, which deserves a closer look by the scientific community.

Reactivity of a nitrosyl ruthenium complex and its potential impact on the fate of DNA - An in vitro investigation

The role of metal complexes on facing DNA has been a topic of major interest. However, metallonitrosyl compounds have been poorly investigated regarding their reactivities and interaction with DNA. A nitrosyl compound, cis-[Ru(bpy)₂(SO₃)(NO)](PF₆)(A), showed a variety of promising biological activities catching our attention. Here, we carried out a series of studies involving the interaction and damage of DNA mediated by the metal complex A and its final product after NO release, cis-[Ru(bpy)₂(SO₃)(H₂O](B). The fate of DNA with these metal complexes was investigated upon light or chemical stimuli using electrophoresis, electronic absorption spectroscopy, circular dichroism, size-exclusion resin, mass spectrometry, electron spin resonance (ESR) and viscometry. Since many biological disorders involve the production of oxidizing species, it is important to evaluate the reactivity of these compounds under such conditions as well. Indeed, the metal complex B exhibited important reactivity with H₂O₂ enabling DNA degradation, with detection of an unusual oxygenated intermediate. ESR spectroscopy detected mainly the DMPO-OOH adduct, which only emerges if H₂O₂ and O₂ are present together. This result indicated HOO^• as a key radical likely involved in DNA damage as supported by agarose gel electrophoresis. Notably, the nitrosyl ruthenium complex did not show evidence of direct DNA damage. However, its aqua product should be carefully considered as potentially harmful to DNA deserving further in vivo studies to better address any genotoxicity.

Bioinformatics analysis for the purpose of designing a novel multi-epitope DNA vaccine against Leishmania major

Leishmaniasis is one of the main infectious diseases worldwide. In the midst of all the different forms of the disease, Cutaneous Leishmania (CL) has the highest incidence in the world. Many trial vaccines have been developed with the purpose of generating long-term cell-mediated immunity to Leishmania(L) major. As there is not any multi-epitope DNA vaccine with high efficacy against L.major, the aim of this study is to design a new multi-epitope DNA vaccine in order to have effective control upon this infectious disease through the immune bioinformatics. The L.major antigens: Gp63, LACK, TSA, LmSTI1and KMP11 were selected to design a multi-epitope DNA vaccine. The initial structure of the DNA vaccine was designed, benefiting from Gen Bank's website information. Epitopes of MHC-I antigens were predicted through the Immune Epitope Database (IEDB), and the selected epitopes were used to make vaccines construct along with linkers. New multi-epitope vaccine including 459 nucleic acids designed, and inserted between BamH1 and HindIII restriction sites of pCDNA3.1 mammalian expression vector. 12 epitopes among the chosen antigens were selected by two servers (IEDB and ANTIGEN). They had high stability and high antigenic power. Physicochemical features of vaccine measured by ProtParam server, and this structure was thermostable and hydrophilic. it's a suitable model to study on the animal and human phases. The designed vaccine is expected to be an effective candidate through development of (CL) vaccines. However, the effectiveness of this vaccine should also evaluate in vivo model.

In vitro and in vivo Anti-leishmanial Potential of [Ag (PTA) 4 ]BF 4 and [Ag(HBPz 3 )(PPh 3 )] Silver Complexes

BACKGROUND

American tegumentary leishmaniasis is a parasitic disease known for being difficult to treat; therefore, the search for more effective therapeutic methods is necessary. The objective of this study was to evaluate the in vitro and in vivo antileishmanial activity of silver complexes [Ag(PTA)4]BF4 (Ag1) and [Ag(HBPz3)(PPh3)] (Ag2) against Leishmania (Leishmania) amazonensis [L. (L.) amazonensis] and Leishmania (Viannia) guyanensis.

METHODS

In vitro bioassays were performed to evaluate the activity of the complexes against promastigote and amastigote forms and evaluate their cytotoxicity. In vivo experiments were performed with hamsters (Mesocricetus auratus) infected and treated topically with two gels containing each metallic complex.

RESULTS

Both complexes reduced the number of viable parasites against the promastigote forms of L. (L.) amazonensis. Ag2 was mainly effective against the amastigote forms. The Ag2 complex did not present cellular cytotoxicity, and regarding the selectivity index, both complexes were considered acceptable, with Ag2 having the best selectivity index in murine peritoneal macrophages in relation to L. (L.) amazonensis. Ag2 showed better results in the topical treatment against infections caused by L. (L.) amazonensis, with a small reduction in the lesion volume after the 14th day of treatment and less parasitic load at the lesion site.

CONCLUSIONS

Ag2 was more effective than Ag1 against L. (L.) amazonensis.

The nitric oxide pathway is involved in the anti-inflammatory effect of the rutheniumcomplex [Ru(bpy)2(2-MIM)(NO)](PF6)3

Metal coordination complexes are chemotherapeutic and anti-inflammatory agents. The ruthenium complex FOR811A ([Ru(bpy)₂(2-MIM)Cl](PF₆)₃) FOR811A was evaluated in mice models of acute inflammation and behavioral tests. Animals received FOR811A (3, 10 or 30 mg/Kg; i.p.), indomethacin (20 mg/Kg; i.p.), L-NAME (20 mg/Kg; i.v.) aminoguanidine (50 mg/Kg; i.p.) or dexamethasone (0.5 mg/Kg; s.c.) 30 min before inflammatory stimulation. Paw edema was induced by carrageenan (400 μg/paw), TNF-α or L-arginine (15 nmol/paw) (5 ng/paw) and evaluated by hydroplestimometry 4 h later. Peritonitis was induced by carrageenan (500 μg; i.p.) and evaluated 4 h later for hypernociception and quantification of total/differential leukocytes, total protein reduced glutathione (GSH) and myeloperoxidase (MPO). FOR811A inhibited the paw edema induced by carrageenan at 3 (64%; p < 0.0001), 10 (73%; p < 0.0001) and 30 mg/kg (66%; p < 0.0001), and at 10 mg/kg that induced with L-arginine by 75% or TNF-α by 55% (p = 0.0012). Paw tissues histological analysis showed reduction in mast cells (46%; p = 0.0027), leukocyte infiltrate (66%; p < 0.0001), edema and hemorrhagic areas. Immunohistochemical evaluation revealed inhibition of iNOS (62%; p < 0.0001) and TNF-α (35%; p < 0.0001). In the peritonitis model FOR811A increased (2.8X; p < 0.0001) hypernociceptive threshold, reduced total leukocytes (29%; p < 0.0001), neutrophils (47%; p = 0.0003) and total proteins (36%; p = 0.0082). FOR811A also inhibited MPO (47%; p = 0.0296) and increased GSH (1.8X; p < 0.0001). In the behavioral tests, FOR811A reduced (30.6%) the number of crossings in the open field, and increased (16%) the number of falls in the Rota rod. Concluding, FOR811A presents anti-inflammatory and antioxidant effects, via nitric oxide pathway.

Ruthenium-nitrosyl complexes as NO-releasing molecules and potential anticancer drugs

The synthesis of new types of mono- and polynuclear ruthenium nitrosyl complexes is driving progress in the field of NO generation for a variety of applications. Light-induced Ru-NO bond dissociation...

The biofilm inhibition activity of a NO donor nanosilica with enhanced antibiotics action

Nitric oxide (NO) has emerged as a promising antibacterial agent, where NO donor compounds have been explored. Here, we investigated the role of a silica nanoparticle containing nitroprusside (MPSi-NP) as a NO donor agent against methicillin-sensitive (ATCC 25,923 and ATCC 12228) and methicillin-resistant (ATCC 700,698 and ATCC 35984) Staphylococcus strains. Biofilm inhibition was studied along with antibiotic activity in combination with standard antibiotics (ampicillin and tetracycline). MPSi-NP exhibited thermal release of 63% of NO within 24 h, while free nitroprusside released only 18% during a dialysis assay, indicating an assisted release of NO mediated by the nanoparticles. This nanomaterial showed only a moderate activity in blocking biofilm production, but exhibited a significant decrease in the number of viable bacterial cells (over 600-fold for Staphylococcus aureus ATCC 700,698 and Staphylococcus epidermidis ATCC 35984). Remarkably, even using MPSi-NP at concentrations below any antibacterial action, its combination with ampicillin promoted a significant decrease in MIC for resistant strains of S. aureus ATCC 700,698 (2-fold) and S. epidermidis ATCC 35,984 (4-fold). A carbopol-based gel formulation with MPSi-NP (0.5% w/w) was prepared and showed a zone of inhibition of 7.7 ± 0.6 mm for S. epidermidis ATCC 35984. Topical use of MPSi-NP in combination with antibiotics might be a manageable strategy to prevent and eventually treat complicated resistant bacterial infections.

An appraisal of the scientific current situation and new perspectives in the treatment of cutaneous leishmaniasis

Leishmaniasis is a Neglected Tropical Diseases caused by protozoan parasites of the genus Leishmania. It is a major health problem in many tropical and subtropical regions of the world and can produce three different clinical manifestations, among which cutaneous leishmaniasis has a higher incidence in the world than the other clinical forms. There are no recognized and reliable means of chemoprophylaxis or vaccination against infections with different forms of leishmaniasis. In addition, chemotherapy, unfortunately, remains, in many respects, unsatisfactory. Therefore, there is a continuing and urgent need for new therapies against leishmaniasis that are safe and effective in inducing a long-term cure. This review summarizes the latest advances in currently available treatments and improvements in the development of drug administration. In addition, an analysis of the in vivo assays was performed and the challenges facing promising strategies to treat CL are discussed. The treatment of leishmaniasis will most likely evolve into an approach that uses multiple therapies simultaneously to reduce the possibility of developing drug resistance. There is a continuous effort to discover new drugs to improve the treatment of leishmaniasis, but this is mainly at the level of individual researchers. Undoubtedly, more funding is needed in this area, as well as greater participation of the pharmaceutical industry to focus efforts on the development of chemotherapeutic agents and vaccines for this and other neglected tropical diseases.

Exploring Innovative Leishmaniasis Treatment: Drug Targets from Pre-Clinical to Clinical Findings

Leishmaniasis is a group of tropical diseases caused by parasitic protozoa belonging to the genus Leishmania. The disease is categorized in cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), and visceral leishmaniasis (VL). The conventional treatment is complex and can present high toxicity and therapeutic failures. Thus, there is a continuing need to develop new treatments. In this review, we focus on the novel molecules described in the literature with potential leishmanicidal activity, categorizing them in pre-clinical (in vitro, in vivo), drug repurposing and clinical research.

Metallodrugs for the Treatment of Trypanosomatid Diseases: Recent Advances and New Insights

Trypanosomatid parasites are responsible for many Neglected Tropical Diseases (NTDs). NTDs are a group of illnesses that prevail in low-income populations, such as in tropical and subtropical areas of Africa, Asia, and the Americas. The three major human diseases caused by trypanosomatids are African trypanosomiasis, Chagas disease and leishmaniasis. There are known drugs for the treatment of these diseases that are used extensively and are affordable; however, the use of these medicines is limited by several drawbacks such as the development of chemo-resistance, side effects such as cardiotoxicity, low selectivity, and others. Therefore, there is a need to develop new chemotherapeutic against these tropical parasitic diseases. Metal-based drugs against NTDs have been discussed over the years as alternative ways to overcome the difficulties presented by approved antiparasitic agents. The study of late transition metal-based drugs as chemotherapeutics is an exciting research field in chemistry, biology, and medicine due to the ability to develop multitarget antiparasitic agents. The evaluation of the late transition metal complexes for the treatment of trypanosomatid diseases is provided here, as well as some insights about their mechanism of action.

A divergent mode of activation of a nitrosyl iron complex with unusual antiangiogenic activity

Nitric oxide (NO) and nitroxyl (HNO) have gained broad attention due to their roles in several physiological and pathophysiological processes. Remarkably, these sibling species can exhibit opposing effects including the promotion of angiogenic activity by NO compared to HNO, which blocks neovascularization. While many NO donors have been developed over the years, interest in HNO has led to the recent emergence of new donors. However, in both cases there is an expressive lack of iron-based compounds. Herein, we explored the novel chemical reactivity and stability of the trans-[Fe(cyclam)(NO)Cl]Cl₂ (cyclam = 1,4,8,11-tetraazacyclotetradecane) complex. Interestingly, the half-life (t_1/2) for NO release was 1.8 min upon light irradiation, vs 5.4 h upon thermal activation at 37 °C. Importantly, spectroscopic evidence supported the generation of HNO rather than NO induced by glutathione. Moreover, we observed significant inhibition of NO donor- or hypoxia-induced HIF-1α (hypoxia-inducible factor 1α) accumulation in breast cancer cells, as well as reduced vascular tube formation by endothelial cells pretreated with the trans-[Fe(cyclam)(NO)Cl]Cl₂ complex. Together, these studies provide the first example of an iron-nitrosyl complex with anti-angiogenic activity as well as the potential dual activity of this compound as a NO/HNO releasing agent, which warrants further pharmacological investigation.

Nitro-imidazole-based ruthenium complexes with antioxidant and anti-inflammatory activities

Inflammation is a physiological process triggered in response to tissue damage, and involves events related to cell recruitment, cytokines release and reactive oxygen species (ROS) production. Failing to control the process duration lead to chronification and may be associated with the development of various pathologies, including autoimmune diseases and cancer. Considering the pharmacological potential of metal-based compounds, two new ruthenium complexes were synthesized: cis-[Ru(NO₂)(bpy)₂(5NIM)]PF₆ (1) and cis-[RuCl(bpy)₂(MTZ)]PF₆ (2), where bpy = 2,2'-bipyridine, 5NIM = 5-nitroimidazole and MTZ = metronidazole. Both products were characterized by spectroscopic techniques, followed by Density Functional Theory (DFT) calculations in order to support experimental findings. Afterwards, their in vitro cytotoxic, antioxidant and anti-inflammatory activities were investigated. Compounds 1 and 2 presented expressive in vitro antioxidant activity, reducing lipid peroxidation and decreasing intracellular ROS levels with comparable effectiveness to the standard steroidal drug dexamethasone or α-tocopherol. These complexes showed no noticeable cytotoxicity on the tested cancer cell lines. Bactericidal assay against metronidazole-resistant Helicobacter pylori, a microorganism able to disrupt oxidative balance, unraveled compound 1 moderate activity over that strain. Besides this, it was able to inhibit interleukin-6 (IL-6) and tumor necrosis factor-α (TNF- α) production as well as interleukin-1β (IL-1β) and cyclooxygenase-2 (COX-2) expression in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. This latter activity is remarkable, which has not been reported for other ruthenium-based complexes. Altogether, these results suggest cis-[Ru(NO₂)(bpy)₂(5NIM)]PF₆ complex has potential pharmacological application as an anti-inflammatory agent that deserve further biological investigation.

Synthesis, crystal structure and leishmanicidal activity of new trimethoprim Ru(III), Cu(II) and Pt(II) metal complexes

Leishmaniasis is a parasitic disease caused by protozoa of the genus Leishmania, which has very limited treatment options and affects poor and underdeveloped populations. The current treatment is plagued by many complications, such as high toxicity, high cost and resistance to parasites; therefore, novel therapeutic agents are urgently needed. Herein, the synthesis, characterization and in vitro leishmanicidal potential of new complexes with the general formula [RuCl₃(TMP)(dppb)] (1), [PtCl(TMP)(PPh₃)₂]PF₆ (2) and [Cu(CH₃COO)₂(TMP)₂]·DMF (3) (dppb = 1,4-bis(diphenylphosphino)butane, PPH₃ = triphenylphosphine and TMP = trimethoprim) were evaluated. The complexes were characterized by infrared, UV-vis, cyclic voltammetry, molar conductance measurements, elemental analysis and NMR experiments. Also, the geometry of (2) and (3) were determined by single crystal X-ray diffraction. Despite being less potent against promastigote L. amazonensis proliferation than amphotericin B reference drug (IC₅₀ = 0.09 ± 0.02 μM), complex (2) (IC₅₀ = 3.6 ± 1.5 μM) was several times less cytotoxic (CC₅₀ = 17.8 μM, SI = 4.9) in comparison with amphotericin B (CC₅₀ = 3.3 μM, SI = 36.6) and gentian violet control (CC₅₀ = 0.8 μM). Additionally, complex (2) inhibited J774 macrophage infection and amastigote number by macrophages (IC₅₀ = 6.6 and SI = 2.7). Outstandingly, complex (2) was shown to be a promising candidate for a new leishmanicidal therapeutic agent, considering its biological power combined with low toxicity.

Alkyl gallium(III) quinolinolates: A new class of highly selective anti-leishmanial agents

A series of eight alkyl gallium complexes of general formulae [GaMe₂(L)] and [Ga(Me)₂L] have been synthesised, characterised and their antimicrobial activity against bacteria, cancer cells and Leishmania assessed. All eight complexes are novel, with the solid-state structures of all complexes successfully authenticated by single crystal X-ray diffraction. The dimethyl complexes all adopt a four-coordinate tetrahedral confirmation, while the monomethyl complexes are five-coordinate trigonal bipyramidal. All complexes were screened for their anti-bacterial activity either by solution state diffusion, or a solid-state stab test. The five soluble complexes underwent testing against two differing mammalian cell controls, with excellent selectivity observed against COS-7 cells, with an IC₅₀ range of 88.5 μM to ≥100 μM. Each soluble complex was also tested for their anti-cancer capabilities, with no significant activity observed. Excellent activity was exhibited against the protozoan parasite Leishmania major (strain: V121) in both the promastigote and amastigote forms, with IC₅₀ values ranging from 1.11 μM-13.4 μM for their anti-promastigote activity and % infection values of 3.5% ± 0.65-11.5% ± 0.65 for the more clinically relevant amastigote. Selectivity indices for each were found to be in the ranges of 6.61-64.7, with significant selectivity noted for two of the complexes. At minimum, the gallium complexes show a 3-fold enhancement in activity towards the Leishmaniaamastigotes over the parent quinolinols alone.